This invention relates generally to carbon dioxide indicating apparatus and more particularly relates to carbon dioxide indicating apparatus particularly useful with respiratory circuits, or breathing circuits, to determine whether the gas in such circuits contains carbon dioxide. Further, the carbon dioxide indicating apparatus of the present invention is particularly useful in determining concentrations of carbon dioxide in the above-noted gas. Still further particularly, the carbon dioxide indicating apparatus of the present invention is particularly useful in determining the correct placement of an intubation tube, or endotracheal tube, in the trachea of a patient.
Numerous carbon dioxide indicating apparatus are known to the art. For example, U.S. Pat. No. 5,005,572, patented Apr. 9, 1991, entitled CO2 INDICATOR AND THE USE THEREOF TO EVALUATE THE PLACEMENT OF TRACHEAL TUBES, Raemer et al., inventors, discloses carbon dioxide indicating apparatus; this patent is hereby incorporated herein by reference as if fully reproduced herein. This incorporated patent discloses CO2 indicators particularly useful for determining whether a tracheal tube is properly positioned within the trachea of a patient or improperly positioned in the patient's esophagus. This determination, as taught in detail in this incorporated patent, can be of lifesaving consequences. This determination, as also taught in detail in this incorporated patent, is based on the accepted reports that gas, such as a patient's exhalation gas, expelled from the patient's trachea contains from 4% to 6% CO2 while gas expelled from the patient's esophagus contains no or extremely small amounts of CO2. Accordingly, upon the CO2 indicating device of this incorporated patent indicating the presence of carbon dioxide in such range, it is determined that the tracheal tube has been correctly positioned in the trachea of the patient and if such carbon dioxide concentration is not indicated, the determination is made that the tracheal tube has been incorrectly positioned in the patient's esophagus.
Carbon dioxide indicating apparatus are known to the art such as, for example, the device shown in FIG. 1 of U.S. Pat. No. 4,879,999 patented Nov. 14, 1989, entitled DEVICE FOR THE DETERMINATION OF PROPER ENDOTRACHEAL TUBE PLACEMENT, Leiman et al. inventors. Upon the CO2 indicator 12 of the embodiment shown in FIG. 1 failing, the entire endotracheal tube must be removed causing interruption of the patient anesthesia/ventilation procedure. Such endotracheal tube extubation and interruption of the patient's anesthesia/ventilation procedure is undesirable.
Carbon dioxide indicators are further useful in connection with other medical devices such as, for example, for being placed in the inspiratory path of a patient's anesthesia/ventilating circuit to determine if the carbon dioxide absorber is functioning properly and removing the desired carbon dioxide. This need is disclosed in lines 18:35 of column 1 of U.S. Pat. No. 2,890,177, patented Jun. 9, 1959, CARBON DIOXIDE INDICATOR, Kilmer inventor. This patent is hereby incorporated by reference as if fully reproduced herein.
A calorimetric carbon dioxide indicator known to the art and referred to as the Colibri calorimetric carbon dioxide indicator includes a male luer for connection to the female luer provided on the tubular member through which gas containing carbon dioxide, such as a patient's exhalation gas, flows. The Colibri calorimetric carbon dioxide indicator includes a trapezoidal carbon dioxide indicator provided with indicia indicative of various concentrations of carbon dioxide and which indicator turns different colors upon detecting different carbon dioxide concentrations. The Colibri carbon dioxide indicator is aligned axially with its male luer connector.
Accordingly, there is a need in the art for new and improved CO2 detection or indicating apparatus and particularly new and improved carbon dioxide indicating apparatus that can be removed or replaced without interruption of the patient anesthesia/ventilation procedure.